Dewalt DW788 20" scrollsaw help

[bhiebeler]

I have discovered that I am not to increase the blade tention.  The dewalt service center said it is a a adjustment which works, but stop after a while.  The have told me how to adjust it, but never why.  From further investigation I discovered that when changing blades is the arm is raise while the tention adjustment is set it loosed its setting.  I have looked at the parts diagram, but do not understand why it looses the setting.  Could anyone send me more information.  I have found documents on the internet on how to adjust it, but nothing seem to tell you why or how this is happening.

thanks,